Connection board, and multi-layer wiring board, substrate for semiconductor package and semiconductor package using connection board, and manufacturing method thereof

ABSTRACT

The present invention provides a connection board that is formed by an insulating resin composition layer made of one layer or two or more layers and a connection conductor that is formed so as to pass through the insulating resin composition layer in its thickness direction at a position where a conductor circuit is connected, and a multi-layer wiring board, a substrate for semiconductor package and a semiconductor package using the connection board, and methods for manufacturing them.

This application is a Divisional application of application Ser. No.12/182,908, filed Jul. 30, 2008, which is a Divisional application ofprior application Ser. No. 10/500,119, filed Jun. 17, 2005, the contentsof which are incorporated herein by reference in their entirety. No.10/500,119 is a National Stage Application, filed under 35 USC 371, ofprior International (PCT) Application No. PCT/JP02/13434, filed Dec. 24,2002.

FIELD OF THE INVENTION

The present invention relates to a connection board, and a multi-layerwiring board, a substrate for semiconductor package, a semiconductorpackage using the connection board, and manufacturing method of them.

BACKGROUND OF THE INVENTION

Recently, the social environment surrounding us has been changinggreatly according to an improvement in information communicationnetwork. Among such changes, the growth of mobile equipments isincluded. Their markets are being extended according to compactness andhigh functionality thereof. For this reason, further compactness ofsemiconductor package and multi-layer wiring substrate which is capableof mounting the package with high density are required. Further,inter-layer connection enabling high density wiring, i.e., technique forforming multiple layers with high density becomes important.

A through-hole connection that drilling and plating processes arecombined is mainly provided as the method of forming plurality layersand widely known. According to this method, however, since holes areformed at all layers, a wiring capacity is limited.

In order to reduce the volume of holes at connecting portions, abuild-up technique that processes of forming an insulating resincomposition layer, drilling and forming a circuit are repeated has beenmainly utilized. The build-up technique is roughly classified into alaser method and a photolithography method. According to the lasermethod, laser irradiation is performed in order to drill an insulatingresin composition layer. On the other hand, according to thephotolithography method, a photosensitive curing agent (photoinitiator)is used for insulating resin composition layer, a photo mask is placedthereon, exposure and development are performed for the layers and thusholes are formed.

Some inter-layer connection methods are proposed in order to obtainfurther reduction in costs and high density. Among such methods, amethod capable of omitting processes of drilling and plating aconductive layer has attracted attention. According to this method, abump is formed on a wiring of substrate by printing a conductive paste.Then, an inter-layer connection insulating material in a state of Bstage and a metallic layer are disposed, the bump is inserted within amold resin by pressing so as to be conductive connected to the metalliclayer. This method that the bump is inserted is published in academicsociety and newspaper, and widely recognized in a field of printedwiring board (Hiroshi Ohira and two other persons, Suggestion of PrintedWiring Board by New Manufacturing Method, A Collection of Papers at theNinth Lecture Meeting Regarding Circuit Mount, ISSN 0916-0043, 15A-10,PP. 55-56, (1995.3.14-16), Takahiro Mori and five other persons,Application and Miniaturization of Substrate Using Inter-LayerConnection Technique Using Bump, A Collection of Papers at the TenthLecture Meeting Regarding Circuit Mount, ISSN 0916-0043, 15A-09, pp.79-80, (1996.3.13-15).

A device that plated wires are embedded into an elastomer such assilicon rubber in its thickness direction is developed and utilized as aconvenient tool for connecting two conductors.

According to the laser method of the prior arts, a selection range ofinsulating materials is large, although drilling can be performed notonly for adjacent layers but also for adjacent layers and next adjacentlayers, there arise problems in that a de-smear treatment is requiredfor removing foreign matters of resin diffused by laser irradiation anda working cost is increased in proportion to the number of holes.

According to the photolithography method, conventional facilities formanufacturing wiring board can be utilized and drilling can be performedat a time and thus a reduction in costs can be advantageouslyaccomplished. Nevertheless, there arise problems in that the resolutionof inter-layer insulating material and heat resistance, moreoverstrength of adhesion between a circuit and an insulating resincomposition layer cannot be accomplished at the same time.

Further, since the bump is formed by printing a conductive paste orplating a metal, the precision of forming the bump relies on the limitof print technology. If the bump is formed by plating, there arises aproblem that it is difficult to suppress height variation of bumpsespecially when diameters of holes are different. Further, the bumpformed of conductive paste has small mechanical strength and may bebroken by pressing pressure. The connection reliability may be decreasedwhen a drilling process is required.

The method in which plated wires are embedded into an elastomer such assilicon rubber such that two layers of conductors are connected witheach other is simple, but it is difficult to embed the wires only intodesired connection positions. If the wires are embedded in a latticeconfiguration, the wires may become obstacles at positions that thewires are not desirably contacted.

SUMMARY OF THE INVENTION

The present invention was developed in the light of the above-describeddrawbacks and an object of the present invention is to provide aconnection board that 1) inter-layer connection can be performed only atrequired positions without performing a drilling step, 2) a strongfilled via structure can be formed, 3) a fine wiring circuit withexcellent connection reliability can be formed, 4) high mechanical andthermal precision can be accomplished and 5) multiple layers can beformed by laminating them at a time, and a multi-layer wiring board, asubstrate for semiconductor package and a semiconductor package usingthe connection board, and manufacturing methods of them.

Namely, the present invention is characterized by the followings.

(1) A connection board comprising an insulating resin composition layerformed of one layer or two or more layers and a connection conductorwhich is formed so as to pass through the insulating resin compositionlayer in its thickness direction at least at a position where aconductor circuit is connected.(2) The connection board according to (1) further comprising a conductorcircuit which is electrically connected to the connection conductor atleast one surface of the connection board.(3) The connection board according to (2), wherein the conductor circuitis a metallic layer.(4) The connection board according to any one of (1) through (3),wherein an exposed portion of the connection conductor is covered withmetal.(5) The connection board according to any one of (1) through (4),wherein one of the insulating resin compositions placed at front andrear outermost layers of the connection board is or both of them aremainly made of thermoplastic resin.(6) A manufacturing method of connection board comprising the steps ofselectively removing a first metallic layer of composite metallic layerformed of, at least, second metallic layer serving as carrier and thefirst metallic layer with different removal condition from the secondmetallic layer to form a connection conductor; forming an insulatingresin composition layer of one layer or two or more layers so as tocover at least side surfaces of the connection conductor; and polishingthe insulating resin composition layer such that the connectionconductor is exposed.(7) The method of manufacturing connection board according to (6),wherein the composite metallic layer is formed of the first metalliclayer, the second metallic layer and a third metallic layer which isdisposed between the first metallic layer and the second metallic layerand has different removal condition from those of the first and secondmetallic layers, the first metallic is selectively removed so that theconnection conductor is formed, and then the third metallic layer isselectively removed.(8) The manufacturing method of connection board of (6) or (7), whereina roughening treatment is performed for a surface of exposed secondmetallic layer at which the insulating resin composition layer isformed.(9) The manufacturing of connection board according to any one of (6)through (8) further comprising a step of selectively removing the secondmetallic layer and forming the conductor circuit after polishing theinsulating resin composition layer so that the connection conductor isexposed.(10) The manufacturing method of connection board according to any oneof (6) through (9) further comprising a step of additionally forming aconductor circuit on the exposed surface of the connection conductorand/or the surface of conductor circuit formed on the surface of theconnection conductor after polishing the insulating resin compositionlayer so that the connection conductor is exposed.(11) The manufacturing method of connection board according to any oneof (6) through (10), wherein an adhesive sheet made of at least oneinsulating resin composition is mounted so as to cover the connectionconductor, heated and pressed, and thus the insulating resin compositionlayer is formed.(12) The manufacturing method of connection board according to any oneof (6) through (11), wherein the side of composite metallic layer withthe connection conductor being thereon at which the connection conductoris not formed is opposed to one side or both sides of supportingsubstrate which is larger than the corresponding side of compositemetallic layer and has higher stiffness than the composite metalliclayer and mounted thereon, predetermined manufacturing steps areperformed for a resultant laminate and then the supporting substrate isremoved therefrom.(13) A multi-layer wiring board in which connection conductors or aconnection conductor and conductor circuit of at least two connectionboards obtained by being arbitrarily selected from connection boardsaccording to any one of (1) through (5) are made into an alloy by solidphase metallic diffusion or melt bonding and conductive connected witheach other, and the connection boards are mechanically connected witheach other by an insulating resin composition.(14) The multi-layer wiring board according to (13), wherein aninsulating resin composition layer of the connection board is a liquidcrystal polymer.(15) A manufacturing method of multi-layer wiring board comprising thesteps of: aligning at least two connection boards obtained by themanufacturing method of connection board according to any one of (6)through (12); and heating, pressing and laminating at a time the alignedconnection boards, so that the connection conductors or the connectionconductor and the conductor circuit are made into an alloy by solidphase metallic diffusion or melt bonding and conductive connected witheach other, and the connection boards are mechanically connected witheach other by an insulating resin composition.(16) The manufacturing method of multi-layer wiring board according to(15), wherein a liquid crystal polymer is used for an insulating resincomposition layer of the connection board.(17) The manufacturing method of multi-layer wiring board according to(15) or (16) further comprising a step of forming an outer layer circuitafter the step of heating, pressing and laminating at a time.(18) The manufacturing method of multi-layer wiring board according toany one of (15) through (17), wherein a substrate having a conductorcircuit and/or a metallic foil is laminated at a time together with theconnection board.(19) A substrate for semiconductor package manufactured by themulti-layer wiring board according to (13) or (14) or the multi-layerwiring board obtained by the manufacturing method according to any oneof (15) through (18).(20) The substrate for semiconductor package according to (19)comprising a cavity at a position where a semiconductor chip is mounted.(21) A manufacturing method of substrate for semiconductor packagecomprising the manufacturing method of multi-layer wiring boardaccording to any one of (15) through (18).(22) The manufacturing method of substrate for semiconductor packageaccording to (21) further comprising a step of forming a cavity at aposition that a semiconductor chip is mounted.(23) A semiconductor package manufactured by using the substrate forsemiconductor package according to (19) or (20).(24) A manufacturing method of semiconductor package comprising themanufacturing method of substrate for semiconductor package according to(21) or (22).(25) The manufacturing method of semiconductor package according to (24)further comprising a step of connecting a semiconductor chip to aconductor circuit.(26) The manufacturing method of semiconductor package according to (24)or (25) further comprising a step of sealing the semiconductor chip by aresin.

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Applications No. 2001-391799 (filed by thesame applicant on Dec. 25, 2001), No. 2002-126594 (filed by the sameapplicant on Apr. 26, 2002) and No. 2002-230095 (filed by the sameapplicant on Aug. 7, 2002) the entire contents of which are incorporatedby reference.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view for explaining an embodiment of thepresent invention.

FIG. 2 is a cross-sectional view showing an embodiment of manufacturingmethod for connection board of the present invention.

FIG. 3 is a cross-sectional view showing the embodiment of the presentinvention.

FIG. 4 is a cross-sectional view showing an embodiment of manufacturingmethod for connection board of the present invention.

FIG. 5 is a cross-sectional view showing a process of laminating at atime connection boards of the present invention so as to manufacture amulti-layer wiring board.

FIG. 6 is a cross-sectional view showing an embodiment of step formanufacturing a substrate for semiconductor package and a semiconductorpackage from the connection board of the present invention.

FIG. 7 is a view of specification of patterns for measuring connectionresistance used in Example 4 of the present invention.

FIGS. 8( a) and (b) are cross-sectional views of step of manufacturingsample for measuring connection resistance used in Example 4 of thepresent invention.

FIG. 9 is a graph showing result of test for connection resistancereliability evaluated in Example 4 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A connection board 11 of the present invention is, for example, as shownin FIG. 1( a), a board for connecting metallic foils 101 and 102 andcomprises an insulating resin composition layer 121 and a connectionconductor 13. The connection conductor 13 is formed so as to passthrough the insulating resin composition layer 121 in its thicknessdirection at least at a position where a conductor circuit is connected.Further, the connection conductor 13 is exposed from at least onesurface of the insulating resin composition layer 121. The connectionconductor 13 may be protruded from the surface of the insulating resincomposition layer 121 or may be embedded into the insulating resincomposition layer 121 from its surface. In the former case, theconnection conductor 13 may be protruded in such a manner that theinsulating resin composition layer 121 is polished to be flat and then ametallic layer 112 is newly added. In the latter case, for example, etchback using etchant of copper may be performed.

As shown in FIG. 1( b), the connection board of the present inventionmay have a conductor circuit 103 at one surface of the insulating resincomposition layer 121. The conductor circuit 103 may be a metallic layer111 as shown in FIG. 1( c). As shown in FIG. 1( d), both surfaces of theconnection conductor 13 including exposed portions are preferablycovered with metallic layers 112. Examples of such metal include metalssuch as copper, indium, zinc, lead, gold, platinum, nickel, palladium,tin, alloys containing at least one type of such metals and metalliclayer of two or more layers. When a conductor circuit made of two ormore layers is connected, it is desirable from a view of improvingconnection reliability between metals that these layers are subjected tosolid phase metallic diffusion and made into an alloy at an interfacetherebetween or that these layers are melt-bonded with each other at atemperature which is equal to or lower than a heating temperature at atime of heating, pressing and laminating at a time.

An embodiment of manufacturing method for connection board of thepresent invention will be described hereinafter with reference to FIG.2.

A composite metallic layer 24 (FIG. 2( a)) is formed of first metalliclayer 21 serving as a connection conductor and second metallic layer 22with different removal condition from the first metallic layer 21. Thefirst metallic layer 21 is selectively removed and thus the connectionconductor 13 is formed (FIG. 2( b)).

A thickness of the first metallic layer 21 is desirably thicker thanthat of desired insulating layer because the connection conductor 13 isformed. Although the thickness must be determined depending on an amountthat the first metallic layer 21 is polished and removed in the nextstep for polishing the insulating resin composition layer 121, thethickness is preferably in a range of 5 to 100 μm. If the thickness issmaller than 5 μm, a distance to conductor circuit to be connectedbecomes small and insulating property may be deteriorated. If thethickness exceeds 100 μm, it is not preferable because the precision ofworking is decreased at a time of removing by etching unnecessaryportions of metallic foil. More preferably, the thickness is in a rangeof 20 to 80 μm.

A thickness of the second metallic layer 22 is preferably in a range of5 to 100 μm. If the thickness is smaller than 5 μm, a mechanicalstrength of the second metallic layer 22 is decreased and thus easilybent when the first metallic layer 21 is selectively removed by etching.If the thickness exceeds 100 μm, it takes a long time to remove laterthe second metallic layer 22, which is not economical. The thickness ispreferably in a range of 10 to 80 μm.

The connection conductor is not especially limited and may be formed byselectively removing unnecessary portions of metallic foil such ascopper foil as described above or may be formed, by metal plating, on ametallic foil with different removal condition in a configuration of theconnection conductor. A thickness of the connection conductor ispreferably in a range of 5 to 100 μm. If the thickness is smaller than 5μm, an inter-layer distance to conductor circuit to be connected becomessmall and insulating property may be inferior. If the thickness exceeds100 μm, it is not preferable because precision of working whenunnecessary portions of metallic foil are removed by etching isdecreased. More preferably, the thickness is in a range of 20 to 80 μm.

Next, the insulating resin composition layer 121 is formed so as tocover the connection conductor 13 (FIG. 2( c)).

The insulating resin composition layer refers to as a layer that acomposition comprising an insulating resin such as thermosetting resin,photo-curing resin, thermoplastic resin is semi-cured and/or cured.

As the aforementioned thermosetting resin, there may be usedthermosetting resins prepared such that at least one resin selected froma group of epoxy resin, bismaleimide-triazine resin, polyimide resin,cyanoacrylate resin, phenol resin, unsaturated polyester resin, melamineresin, urea resin, polyisocyanate resin, furan resin, resorcinol resin,xylene resin, benzguanamine resin, diallylphthalate resin,silicone-modified epoxy resin, silicone-modified polyamidimide resin andbenzcychlobutene resin is mixed with, if necessary, curing agent orcuring accelerator therefor and a resultant mixture is heated so as tobe in a semi-cured state or a cured state.

As the aforementioned photo-curing resin, for example, there may be usedphoto-curing resins prepared such that at least one resin selected froma group of unsaturated polyester resin, polyesteracrylate resin,urethanacrylate resin, siliconacrylate resin and epoxyacrylate resin ismixed with, if necessary, photo-initiator, curing agent or curingaccelerator therefor and a resultant mixture is heated so as to be in asemi-cured state or a cured state.

As the aforementioned thermoplastic resin, for example, there may beused thermoplastic resins prepared such that at least one resin selectedfrom a group of polycarbonate resin, polysulphone resin, polyetherimideresin, thermoplastic polyimide resin, tetrafluoropolyethylene resin,hexafluoropolypropylene resin, polyetheretherketone resin, vinylchloride resin, polyethylene resin, polyamidimide resin,polyphenylensulfide resin, polyoxybenzate resin, aromatic polyesterresin and liquid crystal. Furthermore, what is made into the shape of afilm can be used by heating, forming and cooling at least oneabove-mentioned thermoplastic resin.

The aforementioned insulating resin may be used alone or a mixed body ofdifferent kinds of insulating resins may be used for the insulatingresin composition layer of connection board of the present invention.Further, an insulating resin containing an inorganic filler as a fillermay be used. The inorganic filler is not especially limited andconventionally known inorganic fillers may be used. Examples of theinorganic filler include a conductive particle of nickel, gold orsliver, silica, metal oxide or a resin particle with such materialsbeing metal-plated thereon. In order to maintain an insulation ofinsulating resin composition, a non-conductive filler is used desirably.

It is preferable that the insulating resin composition used for thepresent invention contains a thermoplastic resin because a resin needsnot to be newly applied to a substrate surface at a time of forming aplurality of layers. More preferably, the insulating resin compositionused for the present invention is an insulating resin compositioncontaining a liquid crystal polymer serving as a thermoplastic resin. Ifthe insulating resin composition containing a liquid crystal polymer isused, its linear expansion coefficient can be made to be closer to thatof copper. Thus, it is effective in view of laminating at a time theinsulating resin composition together with connection of connectionconductor. A liquid crystal polymer used for the present inventionpreferably has 180° C. or higher of phase transition temperature fromsmectic phase to nematic phase. A liquid crystal polymer with 280° C. orhigher of the phase transition temperature is more preferably because itcan withstand a reflow treatment temperature for lead-less soldering.Specific examples of liquid crystal polymer include Xydar SRT-300,SRT-500, FSR-315, RC-210, FC-110, FC-120, FC-130 (trade namesmanufactured by Nippon Petrochemicals Co., Ltd.), ECONOL E2000 (tradename manufactured by Sumitomo Chemical Co., Ltd.) series, ECONOL E6000(trade name manufactured by Sumitomo Chemical Co., Ltd.) series, VECTRAA950, VECTRA A130, VECTRA C130, VECTRA A230, VECTRA A410 (trade namesmanufactured by Polyplastics Co., Ltd.), EPE-240G30 (trade namemanufactured by Mitsubishi Kasei Co., Ltd.), RODRUN LC-5000H (trade namemanufactured by Unitika Co., Ltd.), NOVACCRRATE E322G30, E335G30,EPE-240G30 (trade names manufactured by Mitsubishi Chemical Co., Ltd.)and BIAC (trade names manufactured by Japan Gore-Tex Inc.).

An insulating resin composition may be directly applied on a substratesurface with a connection conductor being formed thereat. Alternatively,an insulating resin composition may be applied to a surface of plasticfilm such as polyethylene terephthalate film or metallic foil such ascopper foil, aluminum foil or the like, serving as a carrier. Then, aresultant film is heated and dried so as to produce a dry film adhesivesheet. The adhesive sheet is cut with required size and laminated orpressed on the substrate with the connection conductor being formedthereat. In this way, the insulating resin composition layer may beformed.

A thickness of the insulating resin composition layer is preferably in arange of 1 to 100 μm. If the thickness is smaller than 1 μm, it isdifficult to form the insulating resin composition with uniformthickness not so as its adhesive strength is decreased. If the thicknessexceeds 100 μm, it becomes disadvantageous when making the connectionboard into a thin shape. More preferably, the thickness is in a range of3 to 70 μm.

If air bubbles are contained in the insulating resin composition layercovering the connection conductor, it is not preferable in view ofconnection reliability. Thus, it is more preferable to prevent the airbubbles from existing in the insulating resin composition layer.

The insulating resin composition layer may be formed of one layer or twoor more layers. Nevertheless, it is preferable to form two or morelayers because thermal stress generated at a substrate surface inpressing and polishing steps can be reduced and warpage of connectionboard can be also reduced. If the insulating resin composition layerformed of two or more layers, for example, of two layers is formed, asshown in FIG. 3( a), side surfaces of insulating resin compositionlayers 121 a and 121 b forming the insulating resin composition layer121 may oppose a side surface of the connection conductor 13.Alternatively, as shown in FIG. 3( b), only the side surface of theinsulating resin composition layer 121 a may oppose the side surface ofthe connection conductor 13. If the insulating resin composition withtwo or more layers is formed, types of insulating resin composition tobe used are preferably distinguished by hardness of resin after molding,thickness of resin after molding, difference of molecular orientation,presence or absence of filler, type of filler or its content, averageparticle diameter of filler, particle shape of filler, specific gravityof filler. If a liquid crystal polymer is used when the insulating resincomposition layer is formed into a multi-layer structure, as describedabove, the liquid crystal polymer may be used alone by utilizing itscharacteristic that it easily forms a multi-layer structure itself on abasis of molecular orientation at a time of being formed and thus amulti-layer structure can be provided.

It is preferable to perform a roughening treatment for a surface ofexposed second metallic layer prior to forming of insulating resincomposition layer in view of improving a strength of close contact tothe insulating resin composition.

Then, the insulating resin composition layer 121 formed by theabove-described manner is polished such that the connection conductor 13is exposed. Thus, the connection board of the present invention that theconnection conductor is formed so as to pass through the insulatingresin composition layer in its thickness direction can be obtained (FIG.2( d)). Further, by selectively removing the second metallic layer 22shown in FIG. 2( d), the connection board with the conductor circuit 103shown in FIG. 2( e) can be obtained.

According to the present invention, it is important that the connectionconductor is formed so as to pass through the insulating resincomposition layer in its thickness direction at least at a positionwhere the conductor circuit is connected. Among conventional arts,according to connection tool that wires are embedded into an elastomer,wires are embedded at equal intervals therebetween. Thus, even if aconductor circuit of two layers for connection is shifted a little,connection cannot be performed or connection may be performed atunexpected position. Consequently, it is difficult to connect a fineconductor circuit with high precision. On the other hand, according tothe present invention, a connection conductor cannot be formed atunexpected position and thus a fine circuit can be formed with highprecision.

A metallic foil may be further applied on a surface of connectionconductor exposed by polishing the insulating resin composition layer121 and/or on a surface of conductor circuit formed on a surface of theconnection conductor. Alternatively, a treatment such as a metal platingor an etching may be performed for such surfaces. In this way, aconductor circuit can be added or a metallic film can be applied. Themetallic film can be formed by, for example, a method of performingelectroless copper plating subsequent to application of palladium, avacuum film forming method such as copper sputtering or coppersputtering with chromium being a base, print of metallic paste such assilver paste, substituted or electroless gold plating, electrolysis orelectroless plating of nickel/gold, electrolysis or electroless platingof nickel/palladium/gold or electrolysis or electroless plating of tinor tin alloy.

Moreover, a protruded conductor referred to as a bump may be formed onthe conductor circuit connected to the connection conductor. In order toform the bump on the connection board of the present invention, halfetching is performed in a thickness direction for a portion ofrelatively thick conductor other than the protruded portion, so that theprotruded portion is formed. Then, other portions are removed by etchingso that thinned conductor circuit portion and the protruded portion areleft. Alternatively, after the circuit is formed, only portions ofconnection terminals are made to be thick by plating.

Although the connection board of the present invention is produced byusing a composite metallic layer formed of two layers, as the compositemetallic layer used for the present invention, a composite metalliclayer 4 formed of three layers as shown in FIG. 4( a) is preferably usedfrom an economical point of view.

This is because copper is preferably used for the first metallic layerfrom an economical point of view and it is considered to use nickel orits alloy for the second metallic layer with different etching removalcondition from copper. Nevertheless, nickel or its alloy is moreexpensive than copper. When the composite metallic layer is formed oftwo layers, high mechanical strength is required for the second metalliclayer serving as a support for the connection conductor which is formedfrom the first metallic layer. Thus, a certain thickness is required forthe second metallic layer and a large amount of expensive metal must beused. According to the composite metallic layer with three layers thatis obtained by forming an expensive metallic layer with differentetching removal condition from the first and the second metallic layersso as to be relatively thin between the first metallic layer and thesecond metallic layer, the second metallic layer may be made of copperas the first metallic layer. Consequently, it is economical andexcellent mechanical strength can be provided.

A thickness of the third metallic layer in such composite metallic layerformed of three layers is as small as possible and is preferably in arange of 0.05 to 5 μm. If the thickness is smaller than 0.05 μm, whendeposition defects are generated at a plated film for forming a layer ofnickel or its alloy, because of its small thickness, such defects arenot thoroughly covered by the plated film. Thus, so-called pits (lack ofplating) are generated. When the first metallic layer is removed byetching, the second metallic layer may be eroded, an etchant may beleft, and thus reliability of connection may be decreased. If thethickness exceeds 5 μm, the problems are not presented in steps, but thecost for materials may be increased, which is not economical.Thicknesses of the first and the second metallic layers of the compositemetallic layer with three layers are the same as in the case of theabove-described composite metallic layer formed of two layers.

A method for efficient manufacturing the connection board of the presentinvention by using the composite metallic layer 4 with three layers willbe described hereinafter.

Firstly, the composite metallic layer 4 formed of the first metalliclayer 41, the second metallic layer 42 and the third metallic layer 43is prepared as shown in FIG. 4( a). Then, as shown in FIG. 4( b), anetching resist 44 is formed a shape of the connection conductor 13 bylamination of resist film on the surface of the first metallic layer 41,and then by exposing to light and developing. A rear surface isprotected by laminating the etching resist 44 entirely on the rearsurface and exposing the same to light. Then, the first metallic layer41 is selectively removed by etching. After the resist 44 is removed,the third metallic layer is subsequently removed by etching. As aresult, a composite metallic layer 46 with the connection conductor 13being formed thereat can be obtained (FIG. 4( c)). When a plurality ofcircuits are formed on the composite metallic layer 46, a largerquantity of connection boards can be produced more efficiently.

A surface of the composite metallic layer 46 at which the connectionconductor 13 is not formed opposes a surface of supporting substrate 444which has larger stiffness and area than those of the composite metalliclayer 46 with the connection conductor being formed thereon, and isplaced thereon. Alternatively, a plurality of the composite metalliclayer 46 may oppose both surfaces of the supporting substrate 444 and beplaced thereon. Further, an adhesive sheet that is made of insulatingresin composition and larger than the composite metallic layer 46 isplaced on the connection conductor 13. A resultant laminate is heatedand pressed from both sides and thus an insulating resin compositionlayer 121 is formed (FIG. 4( d)). Thereafter, the insulating resincomposition layer 121 is polished (FIG. 4( e)) such that the surface ofthe connection conductor 13 is exposed and then predetermined steps areperformed. Then, a resultant layer is cut into a sheet withpredetermined size and removed from the supporting substrate 444. Inthis way, the connection board is obtained (FIG. 4( f)). Thepredetermined steps include general steps required for forming aconductor circuit, such as a step of forming a metallic film on anexposed surface of the connection conductor 13 by plating or sputteringand a step of etching the metallic film.

The connection board obtained by performing the above-described steps isnot limited to the configuration shown in FIG. 4( f) and if necessary,connection boards with various configurations can be obtained. Forexample, after the second metallic layer 42 of FIG. 4( f) is selectivelyremoved, the conductor circuit 103 may be formed (FIG. 4( g)).Alternatively, after the entire second metallic layer 42 is removed, theexposed third metallic layer 43 may be removed (FIG. 4( h)). If theconductor circuit 103 is formed, the third metallic layer 43 applied toportions that the conductor circuit 103 is not formed may be removed.

It is efficient and preferable to form the insulating resin compositionlayer by using an adhesive sheet made of insulating resin composition. Aplurality of the same type or different types of sheets may be laminatedand used.

Since the composite metallic layer 46 is not adhered to the supportingsubstrate 444, the connection board can be easily removed from thesubstrate 444 by being cut into a predetermined size. Thus, it ispossible to efficiently manufacture the connection board.

The multi-layer wiring board of the present invention can be obtained insuch a manner that among connection boards obtained by theabove-described manner, two or more connection boards are aligned,heated, pressed and laminated at a time. Further, the substrate with theconductor circuit and/or metallic foil may be laminated at a timetogether with the connection board of the present invention and thus themulti-layer wiring board of the present invention can be formed.

The multi-layer wiring board of the present invention is characterizedin that corresponding conductor circuits of opposing connection board,corresponding connection conductor and corresponding conductor circuitor corresponding connection conductors are made into an alloy by solidphase metallic diffusion or melt-bonding and thus are conduct with eachother and contact surfaces other than contact surfaces of thecorresponding conductor circuits, the corresponding connection conductorand the corresponding conductor circuit or the corresponding connectionconductors are mechanically connected by the insulating resincomposition. The state of “being mechanically connected” refers to as astate of being connected by adhesion and that a mechanical externalforce is required for removal. The mechanical connection is used hereinso as to be distinguished from electric connection, i.e., conductiveconnection. In opposing connection boards, contact surfaces other thancontact surfaces of the corresponding conductor circuits, thecorresponding connection conductor and the corresponding conductorcircuit or the corresponding connection conductors include contactsurfaces of insulating resin composition layers, insulating resincomposition layer and connection conductor and insulating resincomposition layer and conductor circuit.

At a time of laminating at a time, for example, as shown in FIG. 5( a),a connection conductor 13 of connection board I or V and a connectionconductor 13 of connection board II or IV are not on a line extended ina direction of passing through the connection board and thus a crankstructure may be provided. In this case, the conductor circuit may bedeformed and stability of connection resistance may be deteriorated.Thus, it is preferable to use an insulating resin composition with highmodulus of elasticity for insulating resin composition layers 121 of theconnection board II, III and IV at an interior side of multi-layerwiring board. If the insulating resin composition layer 121 is made oftwo or more layers, a resin layer contacting the conductor circuitdesirably has high modulus of elasticity. For example, referring toFIGS. 3( a) and 3(b), the insulating resin composition layer 121 a hashigh modulus of elasticity. Specific value of modulus of elasticity ispreferably equal to or larger than 0.0001 GPa at a heating temperature,and is more preferably equal to or larger than 0.001 Gpa, and isespecially preferably equal to or larger than 0.01 GPa. A dynamicmodulus of elasticity of insulating resin composition can be measured byusing ARES manufactured by Rheometric Scientific FE. Ltd. (parallelplates, a frequency of 1 Hz, a temperature is increased at a rate of 5°C./min.).

An insulating resin composition containing a thermoplastic resin ispreferably used for the insulating resin composition layer serving as anoutermost layer of connection board, and more preferably an insulatingresin composition containing a liquid crystal polymer is used. Further,subsequent to lamination at a time, an outer layer circuit may be formedon the outermost layer of multi-layer wiring board by plating oretching.

A substrate for semiconductor package of the present invention ismanufactured by using the above-described connection board ormulti-layer wiring board. Further, the substrate for semiconductorpackage of the present invention may have a cavity at which asemiconductor chip is mounted.

A manufacturing method for such substrate for semiconductor packageincludes the manufacturing method of the above-described connectionboard or multi-layer wiring board. Further, a step of forming a cavitythat a semiconductor chip is mounted may be provided after the step ofheating, pressing and laminating at a time.

A semiconductor package of the present invention is manufactured byusing the above-described connection board, multi-layer wiring board orsubstrate for semiconductor package. For this reason, a manufacturingmethod of the semiconductor package may include the manufacturing methodof the above-described connection board, multi-layer wiring board orsubstrate for semiconductor package. Further, steps of mounting asemiconductor chip and connecting the semiconductor chip to an outerlayer conductor circuit may be provided. Moreover, a step of sealing thesemiconductor chip by resin may be provided.

At a time of mounting a semiconductor chip, a substrate forsemiconductor package is usually heated from its bottom portion at atemperature of about 200° C. Then, the substrate may be curved becauseof this heating. The chip may be floated and thus a wire bonding stepmay be difficult. This is caused by a difference between a thermalexpansion coefficient of insulating resin composition and that of wiringlayer. For this reason, it is important to make a thermal expansioncoefficient of the insulating resin composition be close to that ofwiring layer made of copper, i.e., about 18 ppm/° C. If a thermosettingresin is used for the insulating resin composition layer for connectionboard, a curved substrate is returned to its original state after asemiconductor chip is mounted. If a thermoplastic resin is used for theinsulating resin composition layer, however, thermal distortion remainsbecause of incline within the thermoplastic resin and the substrate isnot returned to its original state after a semiconductor chip is mountedand remains curved. Accordingly, when a thermoplastic resin is used inthe present invention, as described above, an insulating resincomposition layer with two or more layers is preferably formed. Further,when an adhesive sheet is used, a plurality of sheets with differentthicknesses are preferably laminated so as to form an insulating resincomposition layer. For example, an adhesive sheet with a thickness of 50μm and an adhesive sheet with a thickness of 25 μm are successivelylaminated with each other so as to form an insulating resin compositionlayer. When the amount of polished resin is 20 μm, an unpolished layerwith a thickness of 50 μm and a layer with a thickness of 5 μm remainedas a result of polishing exist at a core portion of base material. Thelayer of 5 μm affects generation of curve, but the layer of 50 μm doesnot affect such generation. Consequently, warpage does not occur at atime of mounting a semiconductor chip. In order to obtain suchstructure, three sheets each of which has a thickness of 25 μm may bepressed.

Example 1

As shown in FIG. 4( a), a composite metallic layer 4 formed of 70 μm offirst metallic layer 41 made of copper, 0.2 μm of third metallic layer43 made of nickel and 35 μm of second metallic layer 42 made of copperwas prepared. As shown in FIG. 4( b), a resist NCP225 or NIT225 (tradename manufactured by Nichigo-Morton Co., Ltd.) serving as an etchingresist 44 was laminated on a surface of the first metallic layer 41under conditions such as 110° C. of roll temperature and 0.6 m/min. ofroll speed, formed under exposure conditions such as 80 mJ/cm² ofaccumulated exposure amount, developed with sodium carbonate solutionand subjected to post-exposure in order to ensure close contact of theresist. A rear surface is completely protected by laminating the etchingresist 44 and exposing it on the same conditions as the above.

Then, an alkaline etching A process solution (trade name manufactured byMeltex Inc.) serving as an etchant which did not erode nickel wassprayed on the first metallic layer 41 and then the first metallic layer41 was selectively removed by etching. In this way, the connectionconductor 13 was formed. Operational conditions at this time wereadjusted such that a density of copper was in a range of 135 to 145 g/l,a density of chlorine was 145 to 170 g/l, a density of ammonium was in arange of 8.0 to 9.2N, a pH was in a range of 8.1 to 8.5 and a specificgravity was in a range of 1.2 to 1.215. A temperature was 50° C. and aspray pressure from above and below was in a range of 0.9 to 1.5 kg/cm².Such conditions were determined such that conditions that a nickel layerserving as the third metallic layer 43 was exposed at all portions otherthan the connection conductor were optimized while adjusting a speed ofconveyer and changing a spray time. Then, the etching resist 44 wasremoved by sodium hydrate solution. The nickel layer serving as thethird metallic layer 43 was selectively removed by etching by usingMELSTRIP N950 (trade name manufactured by Meltex Inc.) and thus a copperlayer serving as the second metallic layer 42 was exposed. Operationalconditions at that time were as follows. 500 ml/l of N-950A of MELSTRIP,100 ml/l of N-950B of MELSTRIP, 100 ml/l of 30% aqueous hydrogenperoxide solution and remaining amount of water were mixed together andsuspended. A resultant solution was heated to 40° C. and applied foreach batch or sprayed (from above and below in a range of 0.9 to 1.5kg/cm²). In this way, the nickel layer serving as the third metalliclayer 43 was selectively removed by etching. Then, a surface treatmentsolution CZ8100 (manufactured by Mec Co., Ltd.) was sprayed onto anexposed surface and a roughening treatment was performed upon theexposed copper surface. As a result, as shown in FIG. 4( c), thecomposite metallic layer 46 with the connection conductor 13 beingformed thereon was obtained.

Next, the composite metallic layer 46 was mounted on both surfaces ofsupporting substrate 444 which has a thickness of about 0.5 mm andlarger stiffness and area than those of the composite metallic layer 46such that the connection conductor 13 is placed at the outside. At thattime, the composite metallic layers 46 were mounted on the both sides ofthe supporting substrate 444 at the same positions. This aligning wascarried out as follows. Namely, guide holes were formed in advance atthe supporting substrate 444 and predetermined positions of thecomposite metallic layers 46 that were to be mounted on its both sides.Then, guide pins were passed through the guide holes, so that aligningwas performed. Thereafter, corners of the composite metallic layers 46and the supporting substrate 444 were fixed by a myler tape or apolyimide tape and the guide pins were removed from the guide holes.Examples of effectively used supporting substrate 444 include 1) asimple substance of copper or SUS, 2) a substrate produced by forming ametallic layer on a surface of base material of polyimide or TEFLON(registered trademark of E.I. Dupont de Nemours and Company), 3) asubstrate produced by forming polyimide or TEFLON (registered trademarkof E.I. Dupont de Nemours and Company) on a surface of core basematerial of copper or SUS. Then, first 50 Hm and next 25 μm of liquidcrystal polymers BIAC (manufactured by Japan Gore-Tex Inc.) serving asadhesive sheets of insulating resin composition were mounted in thatorder so as to cover the entire composite metallic layers 46 mounted onthe both sides of the supporting substrate 444. Further, a polyimidefilm (manufactured by Ube Industries. Ltd.) was placed so as to coverthe adhesive sheet for releasing. Then, a resultant laminate was heatedand pressed from its both sides at a temperature of 333° C. and apressure of 4 MPa for 5 minutes, the releasing film was peeled by thehand and thus a structure 500 shown in FIG. 4( d) was obtained.

As shown in FIG. 4( e), surfaces of the structure 500 were polished atboth sides by roll polishing. At that time, a rotating speed ofpolishing rolls 47 and a load applied at an interval between the rollswere adjusted. Polishing was repeated for four or five times under acondition that 4 μm of thickness was reduced for each polishing and thusan entire surface of the connection conductor was exposed. Namely, anamount of polishing was about 20 μm for each surface of the structure500. After polishing, end portions of the supporting substrate were cutand the connection board was removed from an interface of the supportingsubstrate. If the connection board can be removed from the interface ofthe supporting substrate without cutting the end portions, thesupporting substrate can be repeatedly used and thus a productionefficiency is improved. In a case of substrate produced by formingpolyimide or TEFLON on a surface of core base material made of copper orSUS, the connection bard could be removed without cutting end portionsof the substrate. On the other hand, in cases of substrate produced byforming a metallic layer on a surface of base material made of polyimideor TEFLON (registered trademark of E.I. Dupont de Nemours and Company)and substrate produced by a simple substance of copper or SUS, theconnection board could not be removed from the interface. Nevertheless,the composite metallic layer could be cut at a portion that thesupporting substrate did not contact an insulating resin. Thus, as shownin FIG. 4( f), a connection board that was conducted to a metallic layerand included a connection conductor therein could be obtained. It wasconfirmed that productivity was significantly improved.

Thereafter, the second metallic layer 42 was removed by etching and thusa connection board that had the conductor circuit 103 and contained theconnection conductor 13 therein as shown in FIG. 4( g) could beobtained. Further, after the second metallic layer 42 was entirelyremoved, the third metallic layer 43 was removed and thus a connectionboard with the connection conductor 13 being built therein as shown inFIG. 4( h) could be obtained.

Referring to FIGS. 4( f), 4(g) and 4(h), the insulating resincomposition layer was formed by using 50 μm and 25 μm of two layers ofliquid crystal polymer BIAC. A connection board which had substantiallythe same configuration as in the case of two layers could be obtained byusing 75 μm of liquid crystal polymer.

Example 2

Electroless nickel plating, electroless palladium plating andelectroless gold plating were successively performed upon surfaces ofvarious connection boards obtained in Example 1. Then, the connectionboards subjected to plating treatment were aligned as shown in FIG. 5(a) by guide pins and laminated at a time by pressing again at 333° C. Inthis way, a multi-layer wiring board shown in FIG. 5( b) was producedand its conductive connection by alloy of gold and gold was confirmed.At that time, an insulating resin composition between the connectionboards was melted again and adhered with each other. When either ofsubstitution type electroless tin plating and reduction type electrolesstin plating was utilized for plating of connection boards, a multi-layerwiring board could be produced. Electroless nickel plating, electrolesspalladium plating and electroless gold plating were performed upon aconnection board at an outermost layer and electroless tin plating wasperformed for inner connection boards and thus a multi-layer wiringboard was produced as described above. Conductive connection of themulti-layer wiring board by alloy of gold and tin or tin and tin wasconfirmed. When an insulating resin layer was formed of 75 μm of singlelayer, it was confirmed that a wiring of the outermost layer might betransferred among insulating resin. If the wiring is embedded into theinsulating resin and transferred, the insulating resin layer may beformed of one layer.

Example 3

A substrate for semiconductor package and a semiconductor package wereproduced by using the connection board of FIG. 4( f) obtained inExample 1. Firstly, in order to form a fine circuit on a metallic layer111 by etching, half etching for reducing a thickness of the metalliclayer 111 to 18 μm was performed by spraying an etchant, prepared insuch a manner that 100 g/L of aqueous hydrogen peroxide solution, sulficacid and copper sulfate were mixed with each other and a resultantsolution was adjusted so as to obtain 30 g/L of density of copper, onboth sides of FIG. 6( a) at 35° C. of temperature of solution (FIG. 6(b)). At this time, since the thickness of ends of connection conductoris reduced, soldering balls are easily placed on such thinned endportions.

Then, as shown in FIG. 6( c), the conductor circuit 103 was formed byselectively removing the metallic layer 111 by etching. As shown in FIG.6( d), electroless nickel plating, electroless palladium plating andelectroless gold plating were successively performed upon a surface ofthe conductor and thus a substrate for semiconductor package wasproduced.

Next, as shown in FIG. 6( e), a semiconductor chip with an adhesiveagent being applied to its rear surface was adhered to the substrate forsemiconductor package and fixed thereto. Thereafter, as shown in FIG. 6(f), +25 μm of gold wire was bonded and resin molding was performed bytransfer molding. Soldering balls were connected by performing a hightemperature reflow treatment under nitrogen atmosphere and thus asemiconductor package was produced.

Example 4 Experiment for Confirming Connection

Three layers of foils (copper/nickel/copper=70 μm/0.5 μm/35 μm wereprepared.

Etching was performed for 70 μm of copper foil and two different typesof upper and lower patterns were formed as shown in FIG. 7.

The pattern was transferred to 100 μm of LCP (Liquid Crystal Polymer)such that the side of 70 μm of copper foil opposes the side of LCP andthen 35 μm of copper foil was entirely etched. Further, 0.5 μm of nickelfoil was entirely etched, and then electroless nickel plating andelectroless gold plating were successively performed for an exposedpattern surface of 70 μm of copper foil. In this way, a connection boardwas obtained (FIG. 8( a)). A plated layer 22 had 5 μm of nickel and 0.5μm of gold.

A connection board 72 formed of upper side pattern was aligned with aconnection board 73 formed of lower side patter and these boards werepressed at 330° C. and 4 MPa for 5 minutes (FIG. 8( b)).

Terminal portions of ends of the upper pattern were taken out andconnection resistances of four terminals between patterns were measured.Measurement was performed with n=3, an average value was calculated anda connection resistance one contact was calculated as follows.

The connection resistance was calculated such that a wiring resistanceof unit length was calculated from a difference (9 mm) of pattern lengthbetween pattern No. 1 and pattern No. 2. Assume that the portion thatthe upper side pattern did not contact the lower side pattern (9 mm in acase of pattern No. 1 and 18 mm in a case of pattern No. 2) contributedonly to the wiring resistance and portions that the upper side patterncontacted the lower side pattern (ten portions each of which has an areaof 1 mmφ) contributed only to the connection resistance.

connection resistance per contact=(A−B×C)/D

wherein A represents a measured value of connection resistance betweenpatterns; B represents a wiring resistance per unit length; C representsa length of wiring of portion that the upper side pattern does notcontact the lower side pattern and D represents the number of contactsof the upper side pattern and the lower side pattern. By the value, theconnection resistance per terminal was calculated.

A TCT (Thermal Cycle Test) was performed for a produced test piece. Twotypes of conditions, i.e., −55° C. and 15 minutes to 125° C. 15 minutesand −65° C. and 15 minutes to 150° C. 15 minutes were used. The test wasperformed for each condition for 1000 cycles. As a result, as shown inFIG. 9, after 1000 cycles, 0.2 mΩ or less of connection resistance wasobtained and thus high connection reliability was accomplished.

According to the present invention, a connection board that 1)inter-layer connection can be performed only at required portionswithout performing a step of drilling, 2) a strong filled via structurecan be formed, 3) a fine wiring circuit with excellent connectionreliability can be formed, 4) excellent mechanical and thermal precisioncan be provided and 5) a plurality of layers can be formed by laminationat a time, and a multi-layer wiring board, a substrate for semiconductorpackage and a semiconductor package using the connection board, andmanufacturing methods thereof can be provided.

Those skilled in the art will recognize that the above described is apreferable embodiment of the present invention and many changes andmodifications can be made without departing from the spirit and scope ofthe invention.

1. A multi-layer wiring board obtainable by heating, pressing andlaminating at a time at least two connection boards, wherein each of theconnection boards is formed by a method comprising the steps of:selectively removing a first metallic layer of a composite metalliclayer formed of, at least, a second metallic layer serving as a carrierand the first metallic layer, the first metallic layer having adifferent removal condition from the second metallic layer, to form aconnection conductor; forming an insulating resin composition layer,formed of at least one sub-layer, so as to cover at least side surfacesof the connection conductor; polishing the insulating resin compositionlayer such that at least a side surface of the connection conductor isexposed; and covering the exposed surface of the connection conductorwith metal, wherein the connection conductors of the connection boardsare made into an alloy by solid phase metallic diffusion or melt bondingvia the metal and are conductively connected with each other; and theconnection boards are mechanically connected with each other by theinsulating resin composition layer.
 2. The multi-layer wiring boardaccording to claim 1, wherein at least one of the connection boardsfurther comprises a conductor circuit which is electrically connected tothe connection conductor for at least one surface of the connectionboard; and the conductor circuit is covered with metal.
 3. Themulti-layer wiring board according to claim 2, wherein the conductorcircuit is formed by selectively removing the second metallic layerafter polishing the insulating resin composition layer so that theconnection conductor is exposed.
 4. The multi-layer wiring boardaccording to claim 1, wherein at least one of the connection boards isformed by a method further comprising the step of removing the secondmetallic layer so that a surface of the connection conductor is exposed,whereby surfaces of the connection conductor are exposed through bothsurfaces of the insulating resin composition layer in the thicknessdirection.
 5. The multi-layer wiring board according to claim 4, whereinthe exposed surfaces of the connection conductor are covered with metal.6. The multi-layer wiring board according to claim 1, wherein at leastone sub-layer of the insulating resin composition layer, placed at leastone of front and rear outermost layers of the insulating resincomposition layer, is mainly made of thermoplastic resin.
 7. Themulti-layer wiring board according to claim 1, wherein at least onesub-layer of the insulating resin composition layer, which is at leastone of a front surface layer and a rear surface layer of the insulatingresin composition layer, contains a liquid crystal polymer.
 8. Themulti-layer wiring board according to claim 7, wherein the liquidcrystal polymer has a 180° C. or higher phase transition temperaturefrom smectic phase to nematic phase.
 9. The multi-layer wiring boardaccording to claim 7, wherein the liquid crystal polymer has a 280° C.or higher phase transition temperature from smectic phase to nematicphase.
 10. The multi-layer wiring board according to claim 1, whereinsaid insulating resin composition layer includes at least twosub-layers.
 11. The multi-layer wiring board according to claim 1,wherein the connection conductor is covered with one or more selectedfrom the group consisting of copper, indium, zinc, lead, gold, platinum,nickel, palladium, tin, and alloys thereof.
 12. The multi-layer wiringboard according to claim 1, wherein the connection conductor is coveredwith a metallic film formed by a method of performing electroless copperplating subsequent to application of palladium, copper sputtering orcopper sputtering with chromium being a base, a printing of silverpaste, substituted or electroless gold plating, electrolysis orelectroless plating of nickel/gold, electrolysis or electroless platingof nickel/palladium/gold, or electrolysis or electroless plating of tinor tin alloy.
 13. The multi-layer wiring board according to claim 6,wherein the thermoplastic resin has a modulus of elasticity that isequal to or larger than 0.0001 GPa at a heating temperature.